Eye care practitioners know well that comfort is a driving factor of patients’ contact lens success. The reasons behind discomfort can be challenging for the patient to describe and, ultimately, lead to wear dissatisfaction and dropout. In fact 36% of new contact lens wearers cite discomfort as their reason for dropout, topped only by problems with vision, 41%, according to a published report in Eye & Contact Lens.¹ (Editor’s note: In the e-versions of this article, citations that appear in blue will include hyperlinks to the source material. References are also included at the end of this article.)

Knowing the importance of comfort, contact lens manufacturers keep it at the forefront of their research and development. Here, several manufacturers discuss their research-based approach to enhanced comfortability, specifically as it relates to those daily replacement lenses that can be inventoried in-office.

ALCON

Understanding patient needs, as garnered from a multi-country study of over 7,000 consumers and other studies like it, provides key insights that lead to new developments. Among them is Alcon’s proprietary water gradient lens technology, the innovation behind Dailies Total1 contact lenses, says Carla Mack, O.D., M.B.A., head of global professional affairs for Alcon. High water content, specifically on the lens surface vs. the core, Alcon has found, provides patients with a lens that is breathable and comfortable, matching expressed patient needs.

Specifically, Alcon’s water gradient technology delivers a gradual transition in water content from 33% at its core to nearly 100% at its outermost surface, resulting in a high dk/t of 156 for the Dailies Total1 contact lens.

Contact lens comfort is also supported by a healthy tear film. As such, the company’s Smart-Surface technology, which is a microthin layer of moisture on the lens surface that is more than 80% water (based on data on file), is implemented in the Precision1 lens. This technology allows the lens to meet the needs of patients who have long days, are always on the go, and seek lasting performance with dependable comfort, precise vision, and easy handling and, therefore, experience tear evaporation caused by prolonged digital device use and the reduction of blink rates.

BAUSCH + LOMB

The R&D approach to the Infuse daily disposable lenses involved looking at patient insights, says George Grobe, R&D, Global Vision Care, Bausch + Lomb.

One aim of innovation in this contact lens design was to minimize its impact on the ocular environment or ocular surface homeostasis.

Mr. Grobe says: “During the manufacturing process, the lens material is combined with ProBalance Technology, a proprietary combination of ingredients, inspired by the Tear Film and Ocular Surface Society’s DEWS II report,² that includes osmoprotectants, electrolytes and moisturizers. This technology is infused into the lens material during the manufacturing process, and the proprietary ingredients are released during lens wear. Select ingredients [such as glycerin and potassium] are also retained in the lens throughout a 16-hour wearing experience.” A company study of worn lenses concluded the INFUSE Lens maintains 96% of its moisture for 16 hours.

A great deal of attention in designing the Infuse lens also was given to the optical design to provide lens wearers with a high-quality visual experience, adds Mr. Grobe. The optical design features aspheric anterior and posterior optical surfaces, which provide spherical aberration control across the entire power range.

COOPERVISION

“In terms of material,” says Nancy Keir, O.D., Ph.D., senior director, biological sciences, R&D programs, CooperVision, “using a hydrogel lens that contains silicone means more oxygen will reach the eye. You also want a lens that is soft with excellent wettability, but still easy to handle. But none of that will be helpful if the lens doesn’t fit well, so it still comes back to proper fitting.”

To address this, CooperVision created MyDay lenses, a silicone hydrogel lens, using the company’s Aquaform Technology to create a breathable design that locks in moisture. The toric version also uses the company’s Optimized Toric Lens Geometry for a satisfactory fit. In addition, CooperVision’s clariti 1 day contact lenses have a high-water content, low modulus and high-oxygen transmissibility, supporting all-day comfort, adds Dr. Keir.

From an R&D perspective, she says that adjustments are made through a better understanding of the comfort concerns patients experience and how a contact lens interacts with the eye.

“It’s important to understand what patients mean when they talk about ‘comfort,’ as it’s often used as a catch-all phrase,” adds Michele Andrews, O.D., vice president, professional & government affairs, Americas, CooperVision. “A new study [in Contact Lens & Anterior Eye³] has linked subjective comfort to vision quality, so we’re working closely with ECPs to always first make sure the vision is optimized, as what can be perceived as a comfort problem may actually be a refractive one.”

CooperVision’s OptiExpert app is a tool designed to help ensure eye care practitioners select a lens power that matches the fitting guide. Ultimately, a better fitting contact lens that provides optimal correction will mean better comfort, says Dr. Andrews.

JOHNSON & JOHNSON VISION CARE

“We engineer our material and mechanical design to mimic nature, which, in this case, is the eye,” says Kurt Moody, O.D., F.A.A.O., AAO, CCRT Diplomate and director, North America professional education for Johnson & Johnson Vision Care (J&J), of the Acuvue brand.

Starting from the design standpoint, Dr. Moody says that the decision to utilize a knife edge design (which J&J refers to as their invisible edge), is supported by a study in Eye & Contact Lens, published in 2012.⁴

Lens Material Factors and Their Influence on Lens Comfort

SUPPORTIVE EVIDENCE OF A LINK WITH COMFORT

  Good fit (avoid excessive movement and excessive thickness)

 

   Shorter frequency of replacement

 

  Shorter periods of wear (comfort is worse at the end of day)

 

   Low water content

 

  Good in-eye wettability

 

  Low friction

 

Information sourced from the following: Jones L, Brennan NA, González-Méijome J, et al. The TFOS International Workshop on Contact Lens Discomfort: report of the contact lens materials, design, and care subcommittee. Invest Ophthalmol Vis Sci. 2013;54:TFOS37-TFOS70.

“More than likely the reason why [edge design affects comfort] is the fact that we blink between 12,000 to 14,000 times per day, thus the edge profile comes in contact with our very sensitive ‘lid wiper’ area of our upper and lower eye lids thousands of times throughout the wear cycle,” Dr. Moody says. “We know that trauma to this area can result in ‘lid wiper epitheliopathy,’ a condition which induces contact lens discomfort and ocular dryness.”

On the material side, senofilcon and etafilcon materials both leverage the company’s patented form of polyvinylpyrrolidone (PVP) as a wetting agent. PVP is known to mimic the tear film. The attributes of PVP are referenced in research published in ACS Applied Materials & Interfaces.⁵

“Our tear film is composed of proteins, lipids and mucins and when these components are ‘active,’ meaning not denatured, they have natural immune properties as well as comfort attributes,” says Dr. Moody. “Thus, our aim is to work in concert with them by leveraging their attributes.”

Dr. Moody also cites the coefficient of friction (COF), that is, the measurement of how lubricious a material is, as an essential comfort factor.

“This measurement has been proven to have a very high correlation to comfort,” he says, citing an article published in Investigative Ophthalmology & Visual Science.⁶ Dr. Moody says both materials, senofilcon and etafilcon show promising COF measurements similar to the natural cornea.

VSP

VSP focuses on lens design to overcome comfort issues, says Dave Delle Donne, senior vice president of commercial markets for VSP. Recent studies show comfort can be addressed in terms of the lens surface, he says. Unity BioSync features HydraMist coating, which is an adaptation of Tangible Science’s Hydra-PEG technology on daily disposable silicone hydrogel lenses. Hydra-PEG was developed to improve the comfort of custom corneal and scleral GP lenses and has demonstrated proven success, as shown in a 2019 study presented at the Global Specialty Lens Symposium.

“HydraMist is a 90% water polymer that mimics the eye’s natural tear film,” Mr. Dell Donne explains. “It is permanently bonded to the surface of the contact lens, effectively creating a mucin-like wetting surface on the underlying lens material and shielding it from the ocular surface and tear film. This proprietary moisture-retaining polymer coating stabilizes patients’ tear film and ensures consistent moisture to the eye during all-day wear.”

In addition, other studies suggest that the interaction between the lens edge and the ocular surface at the periphery plays an important role in lens fitting. More specifically, a 2015 study, published in Clinical Ophthalmology,⁷ shows that chisel-edge and semi-round edge lenses produce the highest degrees of conjunctival indentation, while knife and round-edge designs induce the lowest amount.

Unity BioSync with HydraMist daily disposable contact lenses are comprised of a smooth, well-tapered, round-edge profile.

Mr. Delle Donne says: “This edge configuration enhances patient comfort, while resting on the bulbar conjunctiva throughout the wearing period.” OM

REFERENCES

1. Sulley A, Young G, Hunt C, McCready S, Targett MT, Craven R. Retention Rates in New Contact Lens Wearers. Eye Contact Lens. 2018;44 Suppl 1:S273-S282. doi: 10.1097/ICL.0000000000000402. PMID: 28617731.
2. Jones L, Downie LE, Korb D, et al. TFOS DEWS II Management and Therapy Report. Ocul Surf. 2017;15(3):575-628. doi: 10.1016/j.jtos.2017.05.006.
3. Maldonado-Codina C, Corango MN, Read ML, et al. The association of comfort and vision in soft toric contact lens wear. Cont Lens Anterior Eye. 2020;101387. doi: 10.1016/j.clae.2020.11.007.
4. Maïssa C, Guillon M, Garofalo RJ. Contact lens-induced circumlimbal staining in silicone hydrogel contact lenses worn on a daily wear basis. Eye Contact Lens. 2012;38(1):16-26. doi: 10.1097/ICL.0b013e31823bad46. PMID: 22146704.
5. Sterner O, Karageorgaki C, Zurcher M, et al. Reducing Friction in the Eye: A Comparative Study of Lubrication of Surface-Anchored Synthetic and Natural Ocular Mucin Analogues. ACS Appl Mater Interfaces. 2017;9(23):20150-20160. doi.org/10.1021/acsami.6b16425.
6. Jones L, Brennan NA, Gozalez-Meijome J, et al. The TFOS International Workshop n Contact Lens Discomfort: report of the contact lens material, design, and care subcommittee. Invest Ophthalmol Vis Sci. 2013;54(11):TFOS37-70. doi: 10.1167/iovs.13-13215
7. Turhan SA, Toker E. Optical coherence tomography to evaluate the interaction of different edge designs of four different silicone hydrogel lenses with the ocular surface. Clin Ophthalmol. 2015;9:935-942. Published 2015 May 25. doi:10.2147/OPTH.S83798.